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8/2/2019 IITJEE 2012 Solutions Paper-1 Physics Hindi
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Page No # 1
PHYSICS
IIT-JEE 2012
PAPER - 1
PART - : PHYSICS
[k.M- I : ,dy lgh mkj izdkjbl [k.M esa10 cgqfodYi iz'ugSA gj iz'u ds pkj mkj fodYi(A, (B), (C) vkSj(D) gS ftuesals ,d gh lgh gSA
1 . nks cM+h /okZ/kj(vertocal) o laekrj /kkrq IysVksa ds chp1cm dh nwjh gSA os X foHkaokrj dsDC L=kksr lstqM+h gSaA nksuksaIys aVks ds e/; ,d izksVkWu dks fLFkj& voLFkk es a NksM+k tkrk gSA NksMs+tkusds rqjar ckn izksVkWu /oZ ls45 dks.k cukrk gqvkxfr djrk gSA rcX dk eku yxHkx gS %(A) 1 10 5 V (B) 1 10 7 (C) 1 10 9V (D) 10 10 10V
Ans. (A)
Sol.
mg = qE
1.67 10 27
10 = 1.6 10 19
01.0
X
X = 9106.1
67.1V
X = 1 10 9 V2 . ,d crZu esa nks eksy ghfy;e xSl ijek.kq nzO;eku= 4 amu vkSj ,d eksy vkWxZu xSl ijek.kq nzO;eku= 40 amu dk
feJ.k 300 K rkieku ij gSA budh oxZek/;&ewy pky dk vuqikr]vrms ghfy;e / v rms vkWxZu gSS(A) 0.32 (B) 0.45 (C) 2.24 (D*) 3.16Ans. (D)
Sol.
Ar
He
Rms
Rms
mRT3
mRT3
v
v
Ar
He
=10
4
40
m
m
He
Ar
3.16
Code - 4
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PHYSICS3. ,d nzO;eku&jfgr fLiz ax dh ruko &jfgr yEckbZ 4.9cm gSA mldk ,d fljk caf/kr gS vkSj nwljsij ,d NksVk xqVdk yxk
gS fp=k nsf[k;sA ;g fudk; ,d ?k"kZ.k &jfgr {kSfrt(horizontal) lrg ij j[kk gSA le; t =0 ij xqVds dks0.2m [khap
dj fLFkj voLFkk ls NksMk tkrk rc og xqVdk3
rad/s vkofk dk ljy&vkorZ &nksyu djrk gSA Bhd mlh le;
(t=0) ij NksVk dadM v pky ls {kSfrt ls 45 dks.k ij fcanqP ls iz{ksfir fd;k tkrk gSA fcanq P dh fcanqO ls nw jh {kSfrt10m gSA ;fnt = 1s ij dadM xqVds ij fxjrk gS] rc v dk eku gS(g = 10m/s 2 ysa)
(A*) s / m50 (B) s / m51 (C) s / m52 (D) s / m53
4. rhu cgqr cM+h IysVsa] ftudk {ks=kQy cjkcj gS] lekarj o ,d nwljs ds ikl j[kh x;h gSaA mudks vkn'kZ &d ".k &vkSj mudh "ek pkydrk cgqr vf/kd gSA igyh vkSj rhljh IysVksadkse'k%2T vkSj3T rkieku ij j[kk tkrk gSA LFkkbZvoLFkk esa chp dh vFkkZr nwljh IysV dk rkieku gSA
(A) T2
65 41
(B) T4
97 41
(C ) T2
97 41
(D) T)97( 41
Ans. (C)
Sol.
LFkk;h voLFkk ij ek/; ifdk }kjk vo'kksf"kr "ek dh nj] mRlftZr "ek dh nj ds rqY; gSA(3T)4 A(T)4 = A(T)4 A(2T)4
(3T) 4 (T )4 = (T )4 (2T) 4 (2T )4 = (16 + 81) T 4
T = T297
4 / 1
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Page No # 3
PHYSICS
5. ,d iryh ,dleku NM+ fcUnqO ij dhyfdr gS vkSj {kSfrt ry esa ,dleku dks.kh; pkyls ?kwe jgh gSfp=k nsf[k;sAt = 0 ij ,d NksVk dhM+kO ls pyuk 'kq: djds NM+ ds vafre fljst = T le; ij igqp dj :d tkrk gSA dhM+k NM+ dslkis{k ,dleku pky v ls pyrk gSA fudk; dh dks.kh; pky iwjsle; cuh jgrh gSAO ds ifjr% fudk; ij yxus okyscy&vk?kw.kZ dk eku(| |) le; ds lkFk ftl izdkj cnyrk gS mldk loksZRre o.kZu fdl xzkQ esa gS\
(A) (B)
(C) (D)
Ans. (A)
Sol.
mg = qE
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Page No # 4
PHYSICS
1.67 10 27 10 = 1.6 10 19 01.0X
X = 9106.1
67.1V
X = 1 10 9 V
6 Searle's iz;ksx }kjk ;ax izR;kLFkrk xq.kkad]
2ldMLg4
Y fudkyus ds fy, ,d L = 2m yacso d = 0.5mm O;kl ds rkj
dk mi;ksx fd;k x;k gSA HkkjM =2.5 kg yxkus ij rkj dh yEckbZ esal = 0.25mm dh o )h gqbZ Ad vkSjl dks ukiusds fy, e'k% Lwxast vkSj ekbksehVj dk iz;ksx fd;k x;kA nksukas ds fip0.5 mm ,oa nksuksa ds ljdqyj Ldsy ij 100fu'kku gSAY ds fudkysx;s eku esa vf/kdre izlaHkkO; =kqfV esa(A) d vkSjl dh ekiks a esa =kqfV;ksa dk va'knku cjkcj gSA(B ) d dh eki esa =kqfV dk v'kankul dh eki esa =kqfV dsv'kanku dh rqyuk esa nqqxquk gSA(C ) l dh eki esa =kqfV dk v'kankud dh eki esa =kqfV ds v'knku dh rqyuk esanqqxquk gSA(D ) d dh eki esa =kqfV dk v'knkul dh eki esa =kqfV esa v'kanku dh rqyuk esa pkSxquk gSAAns. (A)
Sol. d = =100
5.0mm
y = 2dMLg4
maxyy
+dd
2
ds ekiu esa =kqfV mm25.0mm100 / 5.0
d ds ekiu esa =kqfV25.0100 / 5.0
mm5.0100
5.02
dd
2
ds ekiu ds dkj.ky esa =kqfV= d ds ekiu ds dkj.ky esa =kqfV
7. ,d irys xksyh; dks'k (shell) dk dsaUnz mn~xe ij gSo f=kT;kR gSA ml ij /kukos'k bl izdkj forjhr gS fd i "B&?kuRo
,dleku gSA fo|qr {ks=k ds eku)r(E vkSj fo|qr &foHkoV (r) dk ] dsUnzls nwjhr ds lkFk cnyko dk loksZke o.kZu fdl
xzkQ es a gSA
(A) (B)
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Page No # 5
PHYSICS
(C) (D)
Ans. (D)
Sol.
8. fp=k esa n'kkZ;s vuqlkj nks irys lery&mky ysalksa dks feykdj ,d mHk;ksky ysal cuk gSA igys ysal dk virZukad(n)1.5 vkSj nwljs dk1.2 gSA nksuksa ysalksa ds xksyh; Qydksa dh ork &f=kT;k]R = 14 cm gSA bl mHk;ksky ysal ds fy;s ;fnfcEc nwjh40 cm gks] rc izfrfcEc nwjh gksxh
(A) 280.0 cm (B) 40.0 cm (C) 21.5 cm (D) 13.3 cmAns. (B)
Sol.211 R
1R1)1(
f1
1141
)15.1(f1
1
145.0
f1
1
1411
)12.1(f1
1
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Page No # 6
PHYSICS
142.0
f1
2
21 f1
f1
f1
=14
2.014
5.0
147.0
f1
401
1407
v1
=401
201
4012
v1
v = 40 cm
9. ,d NksVk fiaM m ,d nzO;eku&jfgr /kkxs ls tqM+k gSA /kkxs dk nwljk fljkP ij caf/kr gSa fp=k nsf[k;sA fiaM x y ry esa,dleku dks.kh; pky ls o kh; xfr dj jgk gSA o`k dk dsUnzO ij gSA ;fnO vkSjP fcUnwvksads lkis{k fudkys x;s blfudk; ds dks.kh; laosx e'k%0L vkSj PL gS] rc
(A) OL vkSj PL le; ds lkFk ugh cnyrs gSA
(B) OL le; ds lkFk cnyrk gS] tcfd PL ,dleku gSA
(C) OL ,dleku jgrk gS] tcfd PL le; ds lkFk cnyrk gSA
(D) OL vkSj PL nksuksa le; ds lkFk cnyrs gSA
Ans. (C)
Sol.
L0 dh fn'kk vkSj ifjek.k fu;r gSLP dk ifjek.k fu;r gS ijUrq fn'kk ifjofrZr gSA
10. ;ax f}&fLyV iz;ksx dks rhu ckj e'k% gjk] yky vkSj uhyk izdk'k iz;qDr djds fd;k x;kA ,d ckj esa,d gh iz;ksx fd;kx;kA rhu fat&pkSM+kbZ e'k%C, R vkSj B ikbZ xbZA rc](A) G > B > R (B) B > G > R (C) R > B > G (D) R > G > BAns. (D)
=dD
VIBGYOR c G > BSo R > G > B
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Page No # 7
PHYSICS
[k.M- II : cgqy lgh mkj izdkjbl [k.M esa5 cgqfodYi iz'ugSA gj iz'u ds pkj mkj fodYi(A, (B), (C) vkSj(D) gS ftuesa ls,d ;k vf/kd lghgSA
11. ,d yEcs ikbi ds [kqys fljs esa ,d O;fDr QW wd ekjrk gSA blls ok;q esa ,d rhoz&nkc dk Lian ikbi esa vkxsdh vksj pyrkgSA tc ;g Lian ikbi ds nwljs fljs ij igqWprk gS]rc(A) ,d rhoz&nkc dk Lian O;fDr ds eqWg dh vksj pyus yxrk gS] ;fn ikbi dk nw ljk fljk [kqyk gSA(B) ,d ean&nkc dk Lian O;fDr ds eqWg dh vksj pyus yxrk gS] ;fn ikbi dk nwljk fljk [kqyk gSA(C) ,d ean&nkc dk Lian O;fDr ds eqWg dh vksj pyus yxrk gS] ;fn ikbi dk nw ljk fljk can gSA(D) ,d rhoz&nkc dk Lian O;fDr ds eqWg dh vksj pyus yxrk gS] ;fn ikbi dk nwljk fljk can gSAAns. (B), (D)
Sol. ds ekiu esa =kqfV [kqys fljs ij nkc rjax esa dk dykUrj gksus ds dkj.k lEihMu fojyu ds :i esa ijkofrZr gksxktcfd cUn fljs ij nkc rjax leku dyk es a gksxh vr% lEihM+u lEihMu ds :i esa ijkofrZr gksxkA
12. nzO;eku0.1 kg dk ,d NksVk xqVdk tfM+r vkur ryPQ ij j[kk gSA ry vkSj {kSfrt ds chp dks.k gSA xqVds ij1Ndk cy {kSfrt fn'kk esa mlds lagfr dsUnz ij yx jgk gSA fp=k nsf[k;sA xqVdk fLFkj jgrk gSA ;fn(g = 10 m/s 2 ysa
(A) = 45 (B) > 45 vkSj xqVds ij ?k"kZ.k cyP dh vksj gSA(C) > 45 vkSj xqVds ij ?k"kZ.k cyQ dh vksj gSA(D) < 45 vkSj xqVds ij ?k"kZ.k cyQ dh vksj gSA
Ans. (A), (C)
f = 0, ;fn sin = cos = 45 f, Q dh vksj gksxk, sin > cos > 45
f P dh vksj gksxk, sin < cos < 45
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PHYSICS13. ,d ?kukdkj {ks=k dh Hkqtka vkSj dsUnz mn~xe ij gSaA blesa rhu fcUnq vkos'k j[k gS %+3q (0, 0, 0) ij] q (0, a/4, 0)
ij vkSj q (0, +a/4, 0) A lgh fodYi fodYiksa dk pquko djsaA
(A)2a
x ry ls xqtj jgk dqy oS|qr&yDl]2a
x ry ls xqtj jgs dqy oS|qr&yDl ds cjkcj gSA
(B) 2a
y ry ls xqtj jgk dqy oS|qr&yDl] 2a
y ry ls xqtj jgs dqy oS|qr&yDl ls vf/kd gSA
(C) iwjs ?kukdj {ks =k ls xqtj jgk dqy oS|qr&yDl]0
q gSA
(D)2a
z ry ls xqtj jgk dqy oS|qr&yDl]2a
x ry ls xqtj jgs dqy oS|qr&yDl ls cjkcj gSA
Ans. (A), (C)
Sol. ry x =2a
rFkkx =2a
ds lkis{k lHkh vkos'k lefer fLFkfr esa gSaA vr% nksuksa ryksa ls xqtjusokyk yDl leku gksxk
blh rjg ls y = 2a
rFkky = 2a
ry ls xqtjus okyk yDl leku gksxkA
=000
in qqqq3q
lefer :i ls z =2a
rFkkx =2a
ry ls xqtjus okyk yDl leku gksxkA
14. fp=k esa n'kkZ;s x;s vojks/k&ifjiFk ds fy;s lgh fodYiksa dk pquko djsaA
(A) PQ esa /kkjk 'kwU; gSA(B) S ij foHkoQ ij foHko ls de gSA(C) I 1 = 3A(D) I2 = 2AAns. (A), (B), (C), (D)
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Page No # 9
PHYSICSSol. fuxZr o fuos'kh leferh ds dkj.kP rFkkQ o S rFkkT leku foHko ij gksaxs
R eq = 18126
= 4
1 = 412
= 3A
2= 3
126
12
2 = 2 AVA
VS = 2 4 = 8VVA
VT = 1 8 = 8VVP = VQ PQ ls xqtjusokyh /kkjk= 0 (A)VP = VQ VQ > VS (C)I1 = 3A (B)I2 = 2A (D)
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Page No # 10
PHYSICS
15. ,d LFkku esa ,dleku oS|qr&{ks=k jEE 0 vkSj ,dleku pqEcdh; {ks=k j
BB 0 ,d lkFk fLFkr gSA bl LFkku esa ,d / kukRed fcanq vkos'k dh xfr ij fopkj djsaA le;t = 0 ij bl vkos'k dk osxx y ry esav gS] tksx-v{k ls dks.kcukrk gS rct > 0 ds fy;s dkSulk fodYi lgh gSA@gS\(A) ;fn = 0 , rc vkos'k x z ry esa o kh;&iFk ij ?kwerk gSA(B) ;fn = 0 , rc vkos'k y v{k dh fn'kk easa dqaMfyuh&iFk ij pyrk gSo da qMfyuh dk fip vifjofrZr jgrk gSA(C) ;fn = 10 , rc vkos'ky v{k dh fn'kk easadqaMfyuh&iFk ij pyrk gSo daqMfyuh dk fip le; ds lkFk c
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PHYSICS17. ,d ,dleku O; ?kuRo dh 2R f=kT;k dh xksy fMLd esa ls,d 2R O;kl dh NksVh xksy fMLd fudkydj ,d iVy
(lamina) cuk;k x;k gS fp=k nsf[k,A bl iVy dk tM+Ro&vk?kw.kZO vkSjP ls tkusokys v{kksa ds ifjr% e'k%0 ,oa 1
gSaA nksuksa v{k iVy ds ry ds yEcor~gSaA rc vuqikr0
P fudVre iw.kkd esa D;k gS \
Ans. 3Sol.
I0 = 2)R2()m4( 2
23
mR 2
= mR 2 [8 23
]
=2
13mR 2
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Page No # 12
PHYSICS
IP = 23
(4m) (2R) 2 ]R)R2[(m2mR 22
2
= 24 mR 2 2mR2
11
= 2mR2
37
2132
37
II
O
P= 3
1337
Ans. 3
18. vifjfer yEckbZ vkSjR f=kT;k ds ,d Bksl csyu ij ,d leku vk;ru&vkos 'k&?kuRogSA bles a R/2 f=kT;k ,d [kks[kyk
xksyh;&dks"k csyu dsv{k ij dsfUr gS fp=k nsf[k;sAA v{k ls2R nwjh ij fLFkr fcUnqP ij oS|qr0k16
R23ls fn;k tkrk
gSA rck dk eku D;k gS \
Ans. K = 6
E1 = R2.R.
0
2
E2 = 2
3
0 )R2(8
R.34.
.4
1
E1 E 2 = 424.
R.4
R
00
= 241
14
R
0
=0
96R23
=0
K16R23
K = 6
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PHYSICS
Sol. B = 2 / 3222
0
)XR(2iR
B = 2 / 3222
0
)R3R(2iR
= 2 / 322
0
)R4(2iR
=R16
i
R.2.2
iR 03
20
= NBA cos45
= 21
aR16i
2 20
R28ia20
M =i
R2a
M 2 / 72
0 = R2a2 / P
2
0
P = 7
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